Hello all,
I was wondering if someone could explain to me how the heater unit works on the MKV fitted with the ‘later’ under dash mounted unit? Looking at the photo’s in the MKV Service Manual (page 0.10) it shows the pipework coming from the heater unit and going to the heater tap. What I can’t comprehend is how the water circulates and returns to the water jacket of the engine block? When I bought my car the heater unit was missing but I have recently located a replacement and am about to fit it along with the tap. Naturally I don’t want to damage anything after my hunt to find the heater unit.
Best wishes,
Tim
There should be a long straight pipe running under the exhaust manifolds, with a drain tap in it. This connects to the right hand pipe of the heater unit, and to a brass banjo hose nipple fitting on the water pump with short hoses.
There should also be an L-shaped pipe on the scuttle (firewall) which connects the left hand pipe of the heater unit to the control valve on the scuttle with short hoses.
Another hose connects the control valve to a straight brass hose nipple the rear of the water manifold on the intake side.
Hi Rob,
Thanks for that. How do you get the right angled pipes from the heater unit through the scuttle (firewall)?
I’m guessing that the photo in the Jaguar Service Manual is incorrect or just incomplete as the photo had the motor out to show the instillation?
Do you have a photo of your heater tap showing the return to the water jacket. My heater and the tap are in transit from the seller to me at present.
Also, do you have a photo of the control rod from the dash knob to the tap as I’ll have to fabricate one? I think it has a pin at both ends and is supported by rubber bushes at both ends?
Cheers,
Tim
Hi Tim, be a little cautious of your curiosity when you get the tap. The tap has a greased string wound inside to help with the seal, curiosity can’t easily put it back together once explored. And old taps may not seal well. Another point to consider is that old radiators eventually leak and the interior heater core is an old radiator. Where I live in Southern California, heaters are rarely of use. I have disconnected and cleared all liquid from the inside, later heater in my Mark V so as to never worry about the possible leak. A dry heater cannot leak water onto the fine carpet. I plugged the line at both ends. It looks original in the interior and cannot leak.
Yes, the heater control rod has a funky end with a pin. Once you have collected most of your parts, why don’t you list what is missing? I can look in my spares and on my parts car, you might benefit.
Hi Roger,
Thank you so much for the warning. I am naturally curious, as I’m sure you are too, and will resist pulling it apart until I first test it. If there is an issue I can just install a hidden manual on / off junction between the inlet manifold and the tap. I’m going to have the steel 'radiator’ core replaced with a new copper core which should solve any leaking. No doubt it will outlast my ownership of the car.
My wife has said that she won’t travel in the car until the heater is installed (Happy wife, happy life!). I only use the car in the cooler months over here in Melbourne, Australia, and having a heater is lovely. As it’s hot in Summer, a black un-airconditioned car is not pleasant to drive, so I tend not to drive it at that time of the year. If I do it’s likely to be at night or early in the morning when it’s cooler just to keep the car ticking over.
It’s very nice of you to offer to look for parts from your parts car. I’m constantly delighted with the generosity of fellow Jaguar enthusiasts like you. I’ll probably only need the rod from the heater temperature control knob to the tap as the connecting tubes I’ll make out of copper tube. The rubber hoses are no issue.
Cheers,
Tim
Timothy Fox
Timothy2963@gmail.com
Plate O4 on page O10 shows the right angled pipes coming through the slots in the scuttle, and the L shaped pipe running up to the right angle tap.
The control rod is simple enough. Just a rod with Tee ends and a flexible section.
Hi Rob,
Thank you so much for the two photo’s, they are very helpful. I don’t how critical the flexible part of the rod might be though I’m guessing that it would likely help with alignment?
I don’t think I could manufacture one with the flex in it so will have to hope someone might have one that they are will to sell me?
Kind regards,
Tim
The flex is a modern wonder of the age, for MKIv owners. We just got a straight rod and the T pieces at the end acted as universal. The knob on the dash was sprung and I don’t know about originality but I put a piece of rubber tube in the ends to keep it under tension.
I don’t remember my MK VII heater rod having a flex.
